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[操作系统]iOS 文件下载


iOS 视频音乐类等应用会用到“文件下载”。文件下载在iOS中的实现如下:

1、小文件下载

@interface ViewController () <NSURLConnectionDataDelegate>@property (weak, nonatomic) IBOutlet UIProgressView *progressView;/** 文件数据 */@property (nonatomic, strong) NSMutableData *fileData;/** 文件的总长度 */@property (nonatomic, assign) NSInteger contentLength;@end

 

- (void)viewDidLoad {  [super viewDidLoad];  NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_15.mp4"];  [NSURLConnection connectionWithRequest:[NSURLRequest requestWithURL:url] delegate:self];}#pragma mark - <NSURLConnectionDataDelegate>- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response{  self.contentLength = [response.allHeaderFields[@"Content-Length"] integerValue];  self.fileData = [NSMutableData data];}- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{  [self.fileData appendData:data];  CGFloat progress = 1.0 * self.fileData.length / self.contentLength;  NSLog(@"已下载:%.2f%%", (progress) * 100);  self.progressView.progress = progress;}- (void)connectionDidFinishLoading:(NSURLConnection *)connection{  NSLog(@"下载完毕");    // 将文件写入沙盒中    // 缓存文件夹  NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];    // 文件路径  NSString *file = [caches stringByAppendingPathComponent:@"minion_15.mp4"];    // 写入数据  [self.fileData writeToFile:file atomically:YES];  self.fileData = nil;}

 

2、大文件下载

#define XMGFile [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"minion_15.mp4"]@interface ViewController () <NSURLConnectionDataDelegate>@property (weak, nonatomic) IBOutlet UIProgressView *progressView;/** 文件的总长度 */@property (nonatomic, assign) NSInteger contentLength;/** 当前下载的总长度 */@property (nonatomic, assign) NSInteger currentLength;/** 文件句柄对象 */@property (nonatomic, strong) NSFileHandle *handle;@end

 

- (void)viewDidLoad {  [super viewDidLoad];    NSURL *url = [NSURL URLWithString:@"http://120.25.226.186:32812/resources/videos/minion_15.mp4"];  [NSURLConnection connectionWithRequest:[NSURLRequest requestWithURL:url] delegate:self];}

 

#pragma mark - <NSURLConnectionDataDelegate>/** * 接收到响应的时候:创建一个空的文件 */- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response{  // 获得文件的总长度  self.contentLength = [response.allHeaderFields[@"Content-Length"] integerValue];    // 创建一个空的文件  [[NSFileManager defaultManager] createFileAtPath:XMGFile contents:nil attributes:nil];    // 创建文件句柄  self.handle = [NSFileHandle fileHandleForWritingAtPath:XMGFile];}/** * 接收到具体数据:马上把数据写入一开始创建好的文件 */- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{    // 指定数据的写入位置 -- 文件内容的最后面  [self.handle seekToEndOfFile];    // 写入数据  [self.handle writeData:data];    // 拼接总长度  self.currentLength += data.length;    // 进度  self.progressView.progress = 1.0 * self.currentLength / self.contentLength;}- (void)connectionDidFinishLoading:(NSURLConnection *)connection{  // 关闭handle  [self.handle closeFile];  self.handle = nil;    // 清空长度  self.currentLength = 0;}